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Neurology > Pain & Thermosensation > Flashcards

Flashcards in Pain & Thermosensation Deck (22)
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1
Q

What are the 3 classifications of pain?

A

Nociceptive, Inflammatory & Pathological

2
Q

How is pain from the skin perceived?

A

Well-localised - pricking, stabbing, burning

3
Q

How is pain from the muscles perceived?

A

Poorly-localised - aching, tenderness, cramping

4
Q

How is visceral pain perceived?

A

Poorly-localised - often referred to a somatic structure.

5
Q

What are the classes of nociceptor?

A

Aδ-fibres and C-fibres (NB - not all Aδ- and C-fibres are nociceptors)

6
Q

What do Aδ-fibres do?

A

They are fast-acting mechano- and thermo-receptors

7
Q

What do C-fibres do?

A

They are slow-acting (unmyelinated) polymodal receptors.

8
Q

What is ‘frequency coding’?

A

The phenomenon whereby the rate of action potential discharge correlates with the intensity of the applied stimulus.

9
Q

What are the sub-classifications of Aδ-fibres?

A

Type I - high threshold mechanoreceptors

Type II - mechano- & thermo-receptors

10
Q

What are the sub-classifications of C-fibres?

A

C-MH (mechanical and heat)
C-M (Mechanical only)
C-H (Heat)
C-MiHi (normally insensitive but can be activated by inflammatory mediators)

11
Q

At which laminae of Rexed int he dorsal horn of the spinal cord do nociceptive C- and Aδ-fibres mostly terminate?

A

Laminae I and II. Also V for Aδ-fibres.

12
Q

How do visceral afferents from visceral nociceptors reach the CNS?

A

Following sympathetic pathways into the dorsal horn.

13
Q

What is referred pain?

A

Pain felt in a part of the body other than its actual source.

14
Q

What causes referred pain?

A

Some visceral and skin afferents converge on the same spinothalamic neurones and so the brain can mix-up the signals.

15
Q

What is viscerosomatic pain?

A

A pain resulting due to inflammatory exudate from a diseased organ contacting the soma (body wall) e.g. peritonitis.

16
Q

How does information from Aδ-fibres (lamina I) reach the thalamus?

A

Spinothalamic Tract (STT) - fast

17
Q

How does information from C-fibres reach the brainstem?

A

Spinoreticular Tract (SRT) - slow

18
Q

What is the cognitive outcome of pain signals travelling in the STT?

A

Analysis of the pain - location, severity, type

19
Q

What is the cognitive outcome of pain signals travelling in the SRT?

A

Registering of the emotional/motivation component and suffering - “I don’t like this”.

20
Q

What is “Gate Theory”?

A

Theory that nerve impulses, evoked by injury, are influenced in the spinal cord by other nerve cells that act like gates, either preventing the impulses from getting through, or facilitating their passage.

21
Q

What is counter-stimulation analgesia?

A

Stimulation of non-nociceptive afferents (e.g. Aβ-fibres) to activate lamina II inhibitory interneurons that suppress firing of the projection neurone (rub it better)

22
Q

Is there more than one kind of thermoreceptor?

A

Yes - there are many different kinds, each specifically sensing a certain range of temperature.